Swapping parts between Z10 models

I have a Z10 STL100-3 on which the microphone stopped working; everything else is fine, I just can't speak on the phone/use voice command/record audio. It is possible with a headset, and also, the microphone picks up a small amount of noise if I tap on it or something like that.

I also have a Z10 STL100-4, The Verizon only model, which I got for cheap. The problem is I can only connect to the Edge network as all the carriers where I am (Mexico) are GSM. This phone is basically brand new.

I'm wondering if it's possible to swap the parts out of the 100-4 to my 100-3. Specifically, the main board - are the compatible? I had a repair guy tell me the problem with the phone isn't the mic but it's the main board.